The Free On-line Dictionary of Computing (30 December 2018):

instruction mnemonic

    A word or acronym used in assembly language to
   represent a binary machine instruction operation code.
   Different processors have different instruction sets and
   therefore use a different set of mnemonics to represent
   them.

   E.g. ADD, B (branch), BLT (branch if less than), SVC, MOVE,
   LDR (load register).

   (1997-02-18)